Concentric brake booster with moving hoses

ABSTRACT

A concentric brake booster is disclosed which includes a housing defining a bore therein, a piston shiftable within the bore, and a spool valve slidably mounted within the piston to selectively admit pressurized fluid into the chamber defined between the end of the piston and a corresponding end of the housing to urge the piston in a direction applying the brakes of the vehicle. A portion of the housing is cut away to define an opening therein. The piston is provided with a portion that extends through the opening that houses an inlet port, an outlet port, and a return or exhaust port. Each of the ports are communicated with other fluid appliances in the vehicle hydraulic system by hoses which move with the piston as the latter shifts within the housing. A fluid storage device or accumulator is provided to supply pressurized fluid to the brake booster to be used to shift the piston when a malfunction prevents proper operation of the vehicle&#39;&#39;s power steering pump which normally supplies pressurized fluid to the booster.

United States Patent Goscenski [451 July 18, 1972 [54] CONCENTRIC BRAKEBOOSTER WITH MOVING HOSES [72] Inventor:

[52] US. Cl ..60/54.6 P, 91/6, 60/51 [51] Int. Cl. .FlSb 7/00, F03b F0lb25/02 [58] Field of Search ..60/54.5, 54.6 P, 52 B, 51; 91/6 [56]References Cited UNITED STATES PATENTS Garrison et a1. ..60/5l 722,52011/1965 Canada ..60/54.5P

Primary ExaminerMartin P. Schwadron Assistant Examiner-A. M. ZupcicAtl0rney1(en C. Decker and Plante, Hartz, Smith & Thompson [ ABSTRACT Aconcentric brake booster is disclosed which includes a housing defininga bore therein, a piston shiftable within the bore, and a spool valveslidably mounted within the piston to selectively admit pressurizedfluid into the chamber defined between the end of the piston and acorresponding end of the housing to urge the piston in a directionapplying the brakes of the vehicle. A portion of the housing is cut awayto define an opening therein. The piston is provided with a portion thatextends through the opening that houses an inlet port, an outlet port,and a return or exhaust port. Each of the ports are communicated withother fluid appliances in the vehicle hydraulic system by hoses whichmove with the piston as the latter shifts within the housing. A fluidstorage device or accumulator is provided to supply pressurized fluid tothe brake booster to be used to shift the piston when a malfunctionprevents proper operation of the vehicles power steering pump whichnormally supplies pressurized fluid to the booster.

9 Claims, 1 Drawing Figure CONCENTRIC BRAKE BOOSTER WITH MOVING HOSESBACKGROUND OF THE INVENTION This invention relates to a hydraulic brakebooster.

Because of their smaller size and lower weight, hydraulic brake boostersare expected to be used in lieu of existing vacuum-operated boosters inthe near future. In order to minimize the size of the booster unit, acommon design provides a piston shiftable within the booster housing,and a spool valve which is slidably mounted within the piston itselfthat controls fluid communication into the chamber defined between theend of the piston and the end of the housing for shifting the piston.Such a brake booster is disclosed in copending U.S. Pat. application,Ser. No. 794,472 filed Jan. 15, 1969, owned by the assignee of thepresent invention, and incorporated herein by reference. However, aproblem with the unit disclosed in the aforementioned application, inwhich the valve is mounted within the piston and moves with the latter,is to communicate fluid to the valve. The booster disclosed in theaforementioned patent application provides several close fitting slotsbetween the piston and the housing that receives the fluid that is to becommunicated to the valve. However, this design has proved to be quitedifiicult to manufacture and also requires a number of high pressuresliding seals.

SUMMARY OF THE INVENTION Therefore, an important object of my inventionis to provide a brake booster wherein pressurized fluid is communicateddirectly to the spool valve that is mounted within the piston of thebooster.

Another important object of my invention is to simplify the sealingproblem inherent in existing hydraulic brake boosters.

Another important object of my invention is to provide a brake boosterof minimum size.

Still another important object of my invention is to communicate fluiddirectly to the spool valve housed within the piston used in my brakebooster through hoses that move with the piston as the brakes of thevehicle are applied.

BRIEF DESCRIPTION OF THE DRAWINGS The sole FIGURE of the drawingsschematically illustrates a vehicle hydraulic system with a brakebooster made pursuant to the teachings of my present invention shown incross-section.

DETAILED DESCRIPTION Referring now to the drawing, a brake boosterincludes housing 12 defining a bore 14 therewithin. One end of a boostpiston 16 is slidably mounted in the bore 14, and an elongated rod 18interconnects the other end of the piston 16 with a standard automotivemaster cylinder (not shown) mounted to the left of the booster housing12 (viewing the Figure). A portion of the housing 12 is cut away todefine an elongated opening 20 therein, which exposes a portion of theperiphery of the piston 16. A standard mounting flange 22 is provided onthe housing 12 to mount the brake booster to the firewall of thevehicle.

The piston 16 defines another bore 24 therewithin. A spool valvegenerally indicated at 26 is slidably mounted in the bore 24. The spoolvalve 26 and the bore 24 are provided with spaced recesses that definefluid cavities 28, 30, 32, and 34, therebetween. A portion 36 of thepiston 16 extends through the opening 20 and houses an inlet port 38that communicates the cavity 32 with the outlet of a power steering pump40. An outlet passage 42 provided in the portion 36 communicates thecavity 34 with the inlet of the power steering gear 44. A small passage46 permits metered flow of fluid between the inlet port 38 and theoutlet port 42. A return or exhaust port 48 within the portion 36communicates the cavity 28 with the inlet of the power steering pump 40.The outlet of the power steering gear 44 is also communicated to theinlet of the pump 40.

One end of an operator-actuated control rod 50 is slidably mounted inthe bore 24 and engages the end of the spool valve 26. The other end ofthe control rod 50 is connected to the usual brake pedal (not shown)mounted in the operators compartment of the vehicle. A fluid compartment52 is defined between the other end of the spool valve 26 and thecorresponding end of the bore 24. A flow control device or check valve54 divides the compartment 52 into a first section 56 and a secondsection 58. A first fluid passage 60 communicates the section 58 withthe cavity 30, and a second fluid passage 62 communicates the cavity 30with a chamber 64 defined between the end of the piston and acorresponding end of the housing 12. A spring 66 yieldably urges thespool valve 26 and the rod 50 to the right (viewing the Figure), towardthe brake release position.

Another port 67 within the portion 36 of the piston 16 communicates thesection 56 of the compartment 52 with a fluid storage device oraccumulator 68. Another passage 70 within the portion 36 communicatesthe port 67 with the port 38 to permit flow of fluid into theaccumulator whenever the fluid pressure level in the inlet port 38exceeds the fluid pressure level in the accumulator 68. A check valvegenerally indicated as at 72 prevents reverse flow of fluid from theaccumulator into the inlet port 38.

The check valve 54 includes a valve seat 74 mounted in the compartment52 and a valve member 76 that is normally urged against the seat 74 by aspring 78 to prevent fluid communication through the seat 74. A plunger80 is mounted on the end of the spool valve 26 and is adapted to forcethe valve member 76 ofi the seat 74 thereby permitting fluidcommunication between the sections 56 and 58 of the compartment 52 whenthe spool valve 26 is shifted a sufficient distance.

MODE OF OPERATION The Figure illustrates the relative position of thevarious components of the brake booster 10 when the brakes of thevehicle are released. When the brakes are released, spool valve 26 isdisposed in a position venting the chamber 64 to the inlet of the pump40 through the passage 62, cavities 30 and 28, and the outlet port 48.In this position, the cavity 32 is communicated to the cavity 34 so thatsubstantially all of the fluid flowing in the inlet port 38 iscommunicated directly to the outlet port 42 and from there to the inletof the power steering gear 44. When the vehicle operator effects a brakeapplication, the operator-operated input rod 50 is moved to the leftviewing the Figure, therefore also moving the spool valve 26 to theleft. As the spool valve 26 moves to the left, fluid communicationbetween the cavities 28 and 30 is ter minated, thereby also terminatingfluid communication between the chamber 64 and the inlet of the pump 40,and shortly thereafter fluid communication is initiated between thecavities 30 and 32. A portion of the fluid flowing into the inlet port38 is then directed to the chamber 64 through the cavity 30 and thepassage 62, although most of the fluid continues to flow from the cavity32 to the cavity 34 and out of the outlet port 42. Even if the spoolvalve 26 is shifted far enough such that fluid communication between thecavities 32 and 34 is terminated, fluid still flows between the inletport 38 and the outlet port 42 through the passage 46, thereby assuringan adequate supply of fluid pressure for operating the power steeringgear 44.

The fluid pressure communicated into the chamber 64 through the cavities32 and 30 and the passage 62 acts upon the right hand side of the piston16 (viewing the Figure) to urge the latter to the left to operate themaster cylinder of the vehicle in the normal manner to apply the brakesof the vehicle. The high pressure fluid communicated into the chamber 64is also communicated into the section 58 of the compartment 62 throughthe passage 60. Pressurized fluid in the section 58 acts upon the leftend of the spool valve 26 to create a force opposing movement of thelatter which is transmitted to the input rod 50 and is thereforetransmitted to the vehicle operator. This force is proportional to thefluid pressure level in the chamber 64, and therefore increases as thebrake-applying force is increased, thereby providing proper brake feelto the vehicle operator.

As long as the power steering pump 40 of the vehicle functions normally,an adequate supply of pressurized fluid is assured to operate both thebrake booster l and the power steering gear 44. A portion of this fluidis communicated into the fluid storage device 68 from the inlet port 38through the passage 70 whenever the fluid pressure level in theaccumulator or fluid storage device 68 falls below the fluid pressurelevel in the inlet port 38. Fluid stored in the accumulator 68 is usedto operate the brake booster when the power steering pump 40malfunctions or when the engine of the vehicle ceases to operate whilethe car is in motion. When this occurs, the spool valve 26 is shiftedpast the position wherein fluid communication between the cavities 30and 32 is initiated, and continues to move to the left viewing theFigure until the plunger 80 engages the valve member 76, forcing thelatter from the seat 74 to permit flow of fluid through the seat 74 fromthe accumulator 68 to the section 58 of the compartment 52. Highpressure fluid from the accumulator is then communicated to the chamber64 through the passages 60 and 62 to shift the piston 16 to apply thevehicles brakes in the normal manner. FaiLsafe operation of the brakebooster 10 is therefore assured, even if the power steering pump 40 ofthe vehicle is inoperative.

I claim:

1. In a hydraulic boost device:

a housing defining a first bore therewithin;

a piston slidably mounted in said first bore cooperating with one end ofsaid housing to define a fluid chamber therebetween;

a second bore defined within said piston;

an elongated opening in the wall of said housing exposing a portion ofthe outer surface of said piston;

fluid ports extending through said piston communicating said second borewith the portion of the outer surface of said piston exposed by saidelongated opening;

operator-actuated valve means in said second bore for controlling fluidcommunication between said fluid ports and said chamber, said valvemeans admitting pressurized fluid into said chamber when a brakeapplication is effected to slide said piston; and

conduit means communicating said fluid ports with the vehicle'shydraulic system, said conduit means shifting with said piston relativeto said housing when the piston slides within said housing.

2. The invention of claim 1:

said piston including a portion extending through said elongatedopening:

said conduit means including an inlet port, an outlet port,

and an exhaust port housed within said portion.

3. The invention of claim 1:

said second bore having an inlet port'in fluid communication with apressure source, an outlet port, and an exhaust port in fluidcommunication with a fluid reservoir;

said valve means being slidably mounted in said second bore andshiftable from a first position communicating substantially all of thefluid flowing into the inlet port to the outlet port and communicatingsaid chamber to the exhaust port to a second position communicating atleast a portion of the fluid flowing into the inlet port to said chamberfor shifting said piston.

4. The invention of claim 1:

a fluid compartment within said second bore defined between one end ofthe valve means and a corresponding end of the second bore:

operator-actuated control means extending from said housing foractuating said valve means; and

passage means within said piston for communicating said chamber withsaid compartment to permit pressurized fluid to act upon said one end ofthe valve means whereby a reactive force proportional to the fluidpressure level in said chamber is transmitted to said rod through saidvalve means.

5. The invention of claim 1:

said valve means including a spool valve slidably mounted in said secondbore; and

operator-operated control means for actuating said spool valveprojecting from said housing.

6. In a vehicle hydraulic system having a pressure source, a fluidreservoir; and an accumulator, a hydraulic boost device comprising:

a housing defining a bore therewithin;

a piston slidably mounted within said bore cooperating with said housingto define a fluid chamber between one end of said piston and acorresponding end of said housing;

said housing having an opening extending therethrough exposing a portionof the outer surface of said piston;

said piston defining a second bore therein;

fluid ports extending through said piston communicating said second borewith the portion of the outer surface of said piston exposed by saidelongated opening;

valve means slidably mounted in said piston bore and shiftable from afirst position communicating said chamber to the reservoir to a secondposition communicating said chamber to the pressure source;

conduit means extending through said openings and communicating saidfluid ports with said pressure source, said reservoir, and saidaccumulator, said conduit means shifting with said piston relative tosaid housing when the piston slides within said housing;

said valve means being operative to permit flow of fluid through saidconduit means from the accumulator to the chamber when the valve meansis shifted past the second position and a malfunction prevents a fluidcommunication between the pressure source and the chamber.

7. The invention of claim 6;

said conduit means including passage means communicating saidaccumulator with said second bore; and

normally closed flow control means within said piston for controllingflow of fluid through said passage means;

said valve means being operative to open said flow control means whenthe valve means is shifted a predetermined distance beyond said secondposition.

8. The invention of claim 7:

a fluid compartment within said piston bore defined between one end ofthe valve means and a corresponding end of the piston bore;

said flow control means being mounted in said compartment dividing thelatter into a first section between the control means and the end of thebore and a second section between the control means and the end of thevalve means;

said passage means including a first fluid channel communicating saidaccumulator with said first section and a second fluid channelcommunicating said second section with said chamber; and

means carried on said one end of said valve means for opening said flowcontrol means to permit flow of fluid from accumulator into the chamberupon movement of the valve means a predetermined distance past saidsecond position.

9. The invention of claim 8:

said piston having a portion extending through said opening;

said conduit means including a first section extending between saidpressure source and one of said fluid ports and a second sectionextending between another of said fluid ports and said reservoir;

said first and second sections of said conduit means and said firstfluid channel extending through said portion; and

a fluid passage extending through said portion between said first fluidchannel and the first section of the conduit means to permit flow offluid into the fluid storage device when the pressure level in thelatter is less than the pressure level in the first section of theconduit.

1. In a hydraulic boost device: a housing defining a first boretherewithin; a piston slidably mounted in said first bore cooperatingwith one end of said housing to define a fluid chamber therebetween; asecond bore defined within said piston; an elongated opening in the wallof said housing exposing a portion of the outer surface of said piston;fluid ports extending through said piston communicating said second borewith the portion of the outer surface of said piston exposed by saidelongated opening; operator-actuated valve means in said second bore forcontrolling fluid communication between said fluid ports and saidchamber, said valve means admitting pressurized fluid into said chamberwhen a Brake application is effected to slide said piston; and conduitmeans communicating said fluid ports with the vehicle''s hydraulicsystem, said conduit means shifting with said piston relative to saidhousing when the piston slides within said housing.
 2. The invention ofclaim 1: said piston including a portion extending through saidelongated opening: said conduit means including an inlet port, an outletport, and an exhaust port housed within said portion.
 3. The inventionof claim 1: said second bore having an inlet port in fluid communicationwith a pressure source, an outlet port, and an exhaust port in fluidcommunication with a fluid reservoir; said valve means being slidablymounted in said second bore and shiftable from a first positioncommunicating substantially all of the fluid flowing into the inlet portto the outlet port and communicating said chamber to the exhaust port toa second position communicating at least a portion of the fluid flowinginto the inlet port to said chamber for shifting said piston.
 4. Theinvention of claim 1: a fluid compartment within said second boredefined between one end of the valve means and a corresponding end ofthe second bore: operator-actuated control means extending from saidhousing for actuating said valve means; and passage means within saidpiston for communicating said chamber with said compartment to permitpressurized fluid to act upon said one end of the valve means whereby areactive force proportional to the fluid pressure level in said chamberis transmitted to said rod through said valve means.
 5. The invention ofclaim 1: said valve means including a spool valve slidably mounted insaid second bore; and operator-operated control means for actuating saidspool valve projecting from said housing.
 6. In a vehicle hydraulicsystem having a pressure source, a fluid reservoir, and an accumulator,a hydraulic boost device comprising: a housing defining a boretherewithin; a piston slidably mounted within said bore cooperating withsaid housing to define a fluid chamber between one end of said pistonand a corresponding end of said housing; said housing having an openingextending therethrough exposing a portion of the outer surface of saidpiston; said piston defining a second bore therein; fluid portsextending through said piston communicating said second bore with theportion of the outer surface of said piston exposed by said elongatedopening; valve means slidably mounted in said piston bore and shiftablefrom a first position communicating said chamber to the reservoir to asecond position communicating said chamber to the pressure source;conduit means extending through said openings and communicating saidfluid ports with said pressure source, said reservoir, and saidaccumulator, said conduit means shifting with said piston relative tosaid housing when the piston slides within said housing; said valvemeans being operative to permit flow of fluid through said conduit meansfrom the accumulator to the chamber when the valve means is shifted pastthe second position and a malfunction prevents a fluid communicationbetween the pressure source and the chamber.
 7. The invention of claim6; said conduit means including passage means communicating saidaccumulator with said second bore; and normally closed flow controlmeans within said piston for controlling flow of fluid through saidpassage means; said valve means being operative to open said flowcontrol means when the valve means is shifted a predetermined distancebeyond said second position.
 8. The invention of claim 7: a fluidcompartment within said piston bore defined between one end of the valvemeans and a corresponding end of the piston bore; said flow controlmeans being mounted in said compartment dividing the latter into a firstsection between the control means and the end of the bore and a secondsection between the control means and the end of the valve means; saidpassage means including a first fluid channel communicating saidaccumulator with said first section and a second fluid channelcommunicating said second section with said chamber; and means carriedon said one end of said valve means for opening said flow control meansto permit flow of fluid from accumulator into the chamber upon movementof the valve means a predetermined distance past said second position.9. The invention of claim 8: said piston having a portion extendingthrough said opening; said conduit means including a first sectionextending between said pressure source and one of said fluid ports and asecond section extending between another of said fluid ports and saidreservoir; said first and second sections of said conduit means and saidfirst fluid channel extending through said portion; and a fluid passageextending through said portion between said first fluid channel and thefirst section of the conduit means to permit flow of fluid into thefluid storage device when the pressure level in the latter is less thanthe pressure level in the first section of the conduit.